Everything you need to know about Tia and Colton — the most talked-about pair ahead of this season of 'Bachelor in Paradise'

Tia and Colton have a complicated past and their future is to be continued on the new "Bachelor in Paradise" season. Jesse Grant/Getty Images and Tia Booth/Instagram

Tia and Colton dated before Tia's appearance on "The Bachelor"

Tia was supportive of Colton going on Becca's season of "The Bachelorette," despite still having feelings for him

Colton and Tia will both appear on "Bachelor in Paradise" Season five

Before Becca Kufrin's heart was broken when former-Bachelor Arie Luyendyk Jr. broke off their engagement, fellow-contestant Tia Booth was rumored to be the next Bachelorette. Once Becca's broken-engagement was made public on the finale of "The Bachelor," however; it was clear that Becca would take the role.

Ironically, Tia Booth's time on the show wasn't finished either. It was later revealed that Booth had a past with one of Becca's eligible men, Colton Underwood, who made it all the way to the top four. He was eliminated after Tia told Becca that she still had feelings for him. If Tia and Colton did really have a past, and according to the recent "Bachelor in Paradise" teaser, potentially a future, how long was their relationship and why didn't it work out?

We've rounded up everything you need to know about Tia and Colton's past — and what you can expect this season on paradise.

It all started before Arie's season of "The Bachelor," when Tia Booth was announced as part of the cast.

She was announced as a contestant in December 2017. ABC/Craig Sjodin Tia was announced as a contestant on "The Bachelor" in early December 2017, around the same time that Colton was in the early processes of casting for the next "Bachelorette."

"January tends to be the time where casting limits the guys down to about 50, 25," former-"Bachelor" franchise star Ashley Iaconetti told Access.

The first episode of Arie's season of "The Bachelor" premiered on New Year's Day 2018, but according to Booth, Colton had already followed her on Instagram post-casting announcement, and the two began talking.

The two date during the airing of "The Bachelor."

On the show, Colton told Becca that he had a relationship with Tia prior to filming "The Bachelorette," and that they had "a weekend together," but "the timing wasn't right to grow what was a spark into a flame."

"You really get that final call early February to find out if you've been cast to be a contestant on 'The Bachelorette,'" Iaconetti explained during her talk with Access, "so when [Colton] tells Becca that the timing with Tia wasn't right, it's like yeah, the timing wasn't right because you preferred to be on the show dating the Bachelorette (rather) than a runner up."

When Colton appeared on the Almost Famous podcast, hosted by Iaconetti and former-Bachelor Ben Higgins, he revealed that the weekend they spent together was in Los Angeles and that he rented an Airbnb for the two of them.

"I set everything up," he told them, "we went hiking at Runyon [Canyon] with rescue puppies, we went out to a steak dinner … it was a great date, great weekend."

Colton says Tia knew he was part of the final selection for the show and that she would still say yes if she was offered to be the Bachelorette, but when Becca and her men were chosen, Tia texted him two days before filming, wishing him luck.

"There wasn't enough for me to say, 'Hey this is my person, I'm closing all my options out,'" Colton told Iaconetti and Higgins. Nonetheless, he was still tweeting about Tia all throughout her appearances on "The Bachelor." Once on January 29 writing, "Dr. Tia" with the heart eyes emoji, and again on February 5, writing, "Tia keeps it real."

Colton and Tia's past becomes a major plot on Becca's season of "The Bachelorette."

While on the show, he spoke to Becca about his previous relationship with Tia. ABC "Yeah, they did have a past, so that's something Tia and I had conversations about," Becca told Entertainment Tonight before the season aired. "They dated. I don't know how serious it was, but you'll see all of that unfold throughout the season as well."

Colton said he was surprised to see Tia on the show during his group spa date, but he revealed that the three of them sat together in a scene that wasn't aired and hashed everything out. Tia would later inform Becca that she still had feelings for Colton,and that it made her "sick to her stomach" to hear about them together. Becca then eliminated Colton that same week, although she told him that it wasn't because of anything Tia told her.

"We were all on the same page and moving forward with it," Colton told "Almost Famous" about his past conversation with Becca and Tia at the spa. "It was a little shocking when I heard she came back to talk to Becca."

Colton and Tia will reunite on "Bachelor in Paradise" Season five.

"I feel like me and Colton are just a big question mark," Tia told Entertainment Tonight, "because we haven't gotten to have that conversation about where we stand, about how he feels about me."

"Bachelor" host Chris Harrison chimed in as well before the taping of "Bachelor in Paradise," adding that they "haven't talked." "There's so much tension," he continued to tell E! News. "I feel like that's going to melt down or it's so hot they're just going to make babies."

There's a lot of tears in the teaser trailer for "Bachelor in Paradise" Season five, as Tia seems to be in a love triangle with Colton and Chris R., another contestant on Becca's season of "The Bachelorette" who apologized on the "Men Tell All" episode for telling Becca that she owed him "like 5,000 kisses."

"I don't know what to say," Tia tells Colton as they cry into each other's arms, "I've just been overwhelmed every day."

Later in the trailer a confessional with Chris R. has the contestant revealing not only that "Tia's put the Colton situation behind her," but that he's "falling in love with her more and more every single day."

We'll have to wait and see how it all plays out between Tia and Colton when "Bachelor in Paradise" airs Tuesday at 8 p.m. ET on ABC.